Episode 50 — Counter DDoS, Man-in-the-Middle, and Poisoning Attacks
Origin hardening is where you make your own infrastructure resilient so upstream mitigations have a chance to work and you do not self-destruct under load. Rate limiting at the edge and application tiers, autoscaling policies that produce graceful capacity expansion, and circuit breakers that prevent cascading failures are the operational levers you tune before an attack. Rate limits should be context-aware and tied to identity or session tokens rather than blunt IP caps when possible, and autoscaling must be paired with health probes and throttles so scaling does not amplify the problem. Circuit breakers intentionally fail fast to preserve core functions and allow gradual recovery. Instrumentation matters: application metrics, queue lengths, error rates, and autoscale events form the evidence you will show to explain why you chose to fail or scale at particular thresholds during an incident and how that preserved essential operations.
Man-in-the-Middle, or M I T M, risks live at the intersection of authentication and transport; preventing them relies on rigorous Transport Layer Security, strict transport policies, and additional protections for administrative channels. First, enforce modern Transport Layer Security (T L S) versions and strong cipher suites, and ensure that certificate validation is not bypassed by permissive libraries or client code. HTTP Strict Transport Security, or H S T S, reduces downgrade risk on web browsers, and certificate pinning—where feasible—prevents unauthorized issuers from impersonating your endpoint for high-risk apps. Administrative interfaces should use mutual Transport Layer Security, or m T L S, so both client and server authenticate each other. Beyond cryptography, tooling must validate certificate chains, check revocation via Online Certificate Status Protocol stapling where possible, and record handshake logs that preserve S N I and cert fingerprint evidence for later forensic review.
DNS integrity is critical because name resolution shapes reachability and can be a vehicle for redirection and poisoning; protect it with signed zones, validated resolvers, and strict update controls. Domain Name System Security Extensions, or D N S S E C, adds cryptographic signatures to zone data and prevents off-path tampering of responses, while resolver hardening ensures clients do not silently accept recursive answers from untrusted servers. Limit dynamic updates to authenticated channels and maintain change approval workflows and signed change logs so any zone alteration has a clear provenance. Protect resolver egress with allow-lists and monitor for anomalous high-entropy queries which can indicate tunneling or poisoning attempts. Forensics in DNS incidents are anchored in resolver query logs, zone file histories, and cryptographic key rotation records that show who changed what and when.
Routing integrity is a fundamentally different class of threat but one with massive blast radius; harden routing with best practices for Border Gateway Protocol, filtered announcements, and, where supported, Resource Public Key Infrastructure, or R P K I. Validate customer prefixes, apply strict route filters in the control plane, and avoid accepting unconstrained advertisements from peers. R P K I ties prefix originations to cryptographic attestation, and while adoption varies by region, where available it reduces the risk of accidental or malicious route hijack. Preserve B G P session logs, R P K I validation results, and filter change approvals as auditable items: in an incident you will need the exact route objects, timestamps of announcements, and the change records that led to any modifications.
Rehearsal makes real responses fast and proportionate; practice failover, traffic shifting, and provider coordination so you are not improvising under pressure. Conduct tabletop exercises that simulate activation of scrubbing services, B G P announcements or withdrawals, and C D N reconfiguration. Drill the exact communications with upstream providers and partners, ensure credentials and escalation numbers are current, and rehearse rollbacks so you can restore normal routing without oscillation. Validate autoscaling and circuit-breaker behavior under synthetic attack loads in a controlled environment, and ensure logging captures the sequence of actions for post-mortem review. The output of drills is not just confidence—it is a set of timestamps and artifacts that prove you followed the plan.
Cache poisoning attacks corrupt intermediary caches and cause clients to receive stale or malicious content; defend caches with strict origin validation, secure caching headers, and sanitization of inputs used as cache keys. Ensure that cache keys incorporate canonical request components securely and avoid using untrusted inputs as part of the key. Use signed responses for sensitive content where possible and validate content integrity at the client or proxy with cryptographic means. Apply conservative Time To Live values and require origin verification on cache misses so that a poisoned item is short-lived and easily flushed. Evidence of protection includes cache configuration snapshots, origin validation logs, signed content manifests, and cache hit/miss patterns showing expected behavior during simulated poisoning attempts.
A realistic scenario ties many controls together so you can see choreography and evidence collection in practice. Imagine a mixed D D o S that saturates edge capacity while an attacker attempts a concurrent S S L-stripping, or Secure Sockets Layer stripping, against a subset of clients using a man-in-the-middle vector. Upstream scrubbing reduces volumetric pressure, the C D N terminates most T L S handshakes and preserves certificate integrity at the edge, while your origin enforces H S T S and certificate pinning for critical services. On the local network, port-security and A R P inspection block lateral attempts to place rogue gateways, and you validate DNS with D N S S E C to prevent redirection. Evidence emerges in scrubber summaries, edge certificate logs proving no unauthorized certs were used, local switch violation records, and resolver query traces showing no poisoned answers, allowing coordinated containment while forensic data is gathered.
A compact checklist pairs each family with primary and fallback controls so responders can act without flipping through large manuals. For volumetric D D o S, primary control is upstream scrubbing and anycast; fallback is aggressive edge rate limiting and temporary geo-blocks. For protocol-state exhaustion attacks, primary controls are protocol-aware scrubbing and transport-layer throttles; fallback is service degradation via circuit breakers and staged failover. For application attacks, primary controls are W A F rules and behavioral throttles; fallback is stricter authentication gates or staged feature toggles. For M I T M, primary controls are strict T L S and certificate validation, with m T L S for sensitive admin channels; fallback includes short-term credential rotation and temporary network isolation. For poisoning, primary controls are D N S S E C and controlled updates, with fallback requiring manual overrides and tight resolver whitelists. Keep the checklist terse and executable, and ensure every action produces an auditable artifact.
